Question

I have made a small “webserver” as a mock for my JUnit tests. this is the code of the “webserver”:

while(true) {

    try {
        ServerSocket socket = new ServerSocket(port);
        socket.setReuseAddress(true);
        Socket remote = s.accept();
        PrintWriter out = new PrintWriter(remote.getOutputStream(), true);
        out.append("some data");
        out.flush();
        out.close();    
        remote.close(); 
        socket.close();
    }
    catch (IOException e) { 
        throw new RuntimeException(e);
    }

and this is what i am doing in the code of the program:

    URL url = new URL(urlstr);  
    HttpURLConnection con = (HttpURLConnection) url.openConnection();
    con.connect();
    MyClass myClass = (MyClass) unmarshaller.unmarshal(con.getInputStream());
    con.disconnect();
    return myClass;

here my problem: sometimes it works, sometimes not. and i don’t know why. i get this error:

java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(SocketInputStream.java:180)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:230)
at java.io.BufferedInputStream.read1(BufferedInputStream.java:270)
at java.io.BufferedInputStream.read(BufferedInputStream.java:329)
at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:688)
at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:633)
at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:653)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1067)
at my.program.Program.myMethod(...)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:600)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:73)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:46)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:180)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:41)
at org.junit.runners.ParentRunner$1.evaluate(ParentRunner.java:173)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.ParentRunner.run(ParentRunner.java:220)
at org.junit.runners.Suite.runChild(Suite.java:115)
at org.junit.runners.Suite.runChild(Suite.java:23)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:180)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:41)
at org.junit.runners.ParentRunner$1.evaluate(ParentRunner.java:173)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.ParentRunner.run(ParentRunner.java:220)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

why it’s working sometimes? and why sometimes not? what is wrong? i have to run my junit test 5 or 10 times to get it work one time.

Answer 1

An indirect answer: don’t try to do it yourself. Use an embedded Simple or Jetty server. With roughly the same amount of code, you’ll get a relatively huge amount of functionality beyond what you have, and you won’t encounter strange problems like this, either.

The “connection reset” is happening because you’re closing the socket before the url connection is ready for you to do so.